The invention is in the field of dynamometer testing of aircraft wheel and brake assemblies and, more particularly, relates to the simulation of brake and landing gear vibration dynamics on a dynamometer.
The aircraft landing gear is by nature a complex multi-degree-of-freedom dynamic system. As such, it may encounter various vibratory modes which can be induced by brake frictional characteristics and design features. Aircraft design specification and industry practices require that these modes be assessed during the design concept state and verified during hardware development. Dynamometer simulation of the landing gear is a desirable way to accomplish the necessary brake/landing gear dynamic assessment since brake testing is routinely accomplished by landing a complete wheel, brake, and tire unit against an inertial roadwheel. The requirements for sufficient gear simulation should include the major system degrees-of-freedom that affect the transient brake/landing gear load dynamics. Brake induced vibration and various techniques for simulating such vibration on a dynamometer are discussed in "Brake Dynamics", Aerospace Information Report (AIR) 1064, the Society of Automotive Engineers, Inc., Mar. 30, 1988; "Laboratory Simulation of Landing Gear Pitch-Plane Dynamics", SAE Technical Paper 851937, presented at the Aerospace Technology Conference & Exposition, October 14-17, 1985; and "Realistic Evaluation of Airplane Brake Vibration by Laboratory Test and Analysis", DE-Vol. 84-1, 1995 Design Engineering Technical Conferences Volume 3 - Part A, ASME 1995.
Though these prior techniques are effective in certain respects, an improved dynamometer test apparatus and method are desired that simulates vibrational coupling between braking and gear walk. A more accurate simulation of the motion of the landing gear strut, bogie beam, wheel and brake assemblies, brake rods, and tires on a dynamometer is desired since motion of these components dictates, in part, the amount of damping generated at their mechanical junctures.